Wegovy tablets and Mounjaro are the two most talked-about weight-loss medicines in the UK right now. One is a needle-free tablet taken every morning. The other is a weekly injection. They aren't the same molecule and they don't produce exactly the same results, here's an honest, pharmacist-led comparison to help you decide.

The active ingredients aren't the same

Wegovy tablets contain oral semaglutide, a GLP-1 receptor agonist. Mounjaro contains tirzepatide, which activates both the GLP-1 receptor and a second receptor called GIP. That "dual agonism" is the main reason Mounjaro tends to produce larger average weight loss.

How they're taken

  • Wegovy tablets: once daily, first thing in the morning, on an empty stomach with up to 120ml of plain water, then wait 30 minutes before eating, drinking anything else, or taking other oral medicines.
  • Mounjaro: a single subcutaneous injection once a week using a pre-filled pen, any time of day, with or without food.

Mounjaro is more forgiving on routine; Wegovy tablets are more forgiving on needles.

Average weight loss

  • Wegovy tablets 25mg: around 16.6% average weight loss over 64 weeks in the OASIS-4 trial, with roughly 3 in 10 people losing 20% or more (placebo about 2.7%).
  • Mounjaro 15mg: around 22.5% average weight loss over 72 weeks in the SURMOUNT-1 trial, with more than 1 in 3 losing at least 25%.

Read the numbers carefully. Both are large, clinically meaningful losses; Mounjaro at its top dose is currently the higher-efficacy option. In real-world use, the gap narrows for people who can't tolerate the highest dose of either medicine, and adherence matters more than the trial average.

Titration and time to full dose

Both medicines are stepped up slowly to reduce side effects. Wegovy tablets titrate through 1.5mg → 4mg → 9mg → 25mg with at least a month at each step, roughly four months to maintenance. Mounjaro titrates through 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg, at least four weeks between steps.

Side effects

Both are dominated by gastrointestinal side effects, nausea, constipation, diarrhoea, indigestion, mostly during dose increases and mostly settling within days to a couple of weeks. In OASIS-4 roughly three in four people on the tablet reported gut side effects at some point during titration. Mounjaro's profile is similar. Serious risks (pancreatitis, gallbladder disease, severe dehydration) are uncommon but real for both.

Who each suits

Consider Wegovy tablets if you:

  • Won't or can't self-inject long-term.
  • Can reliably protect a 30-minute empty-stomach window in the morning.
  • Prefer a daily routine (like a tablet) over a weekly appointment with yourself.

Consider Mounjaro if you:

  • Want the highest average weight loss currently licensed in the UK.
  • Prefer a once-weekly medicine with no food-timing rules.
  • Are comfortable with a pen injection under the skin.

Cost, quickly

Both Wegovy tablets and Mounjaro are priced per dose, rising as you titrate up, with delivery charged separately. Pharmacist review is included in both, no separate consultation fee. New customers can use code WELCOME20 at checkout for £20 off their first order. For a full breakdown, see how much Wegovy tablets cost in the UK, or compare against injections with our pill vs injection guide.

Frequently asked questions

Which loses more weight. Wegovy tablets or Mounjaro? On average, Mounjaro at its highest dose produces more weight loss (about 22.5% in SURMOUNT-1) than Wegovy tablets at 25mg (about 16.6% in OASIS-4). Individual results vary, and many people do very well on either.

Are Wegovy tablets and Mounjaro the same medicine? No. Wegovy tablets are oral semaglutide (a single GLP-1 receptor agonist). Mounjaro is tirzepatide, which activates both GLP-1 and GIP receptors. Same medicine class, different molecules.

Can I switch from Mounjaro to Wegovy tablets? Yes. A pharmacist-led switch is possible with a fresh titration. It's a clinical decision based on tolerance, response and preference.

Do Wegovy tablets have fewer side effects than Mounjaro? Both cause gut-related side effects (nausea, constipation, diarrhoea), mostly during dose increases. Neither is clearly gentler on average.

Which is easier to take? Mounjaro is a once-weekly injection with no food-timing rule. Wegovy tablets are once daily on an empty stomach, with a 30-minute wait before eating or drinking anything else. If you can't reliably keep that morning window, the injection may fit better.

References

  1. Wharton S, et al. Oral semaglutide 25 mg in adults with overweight or obesity (OASIS-4). N Engl J Med 2025.
  2. Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022.
  3. MHRA. Authorisation of oral semaglutide (Wegovy tablets), June 2026.

Reviewed by Jimah Alsaai MPharm, GPhC 2232652, Superintendent Pharmacist, Solira.